Yarn tensioning



Oct. 14, 1958 Filed Dec. 22, 1955 J. ssHul I 2,855,749

YARN TENSIONING 2 Sheets-Sheet l INVENTOR Jan fls'buis BY mm WWW A'ITQRNEYS Oct. 14, 1958 J. ESHUIS- 2,855,749 YARN TENSIONING Filed Dec. 22, 1955 2 Sheets-Sheet 2 INVENT OR lhzzllsfiaqls' wda m M ATTORNEYS United States Patent ice 2,s'ss,149 YARN TENSIONING Jan Eshuls, Arnhem, Netherlands, asslgnor, by mesne assignments, to American Enlra Corporation, Enlta, N. C., a corporation of Delaware This invention relates to the stretching of running threads or yarns and more particularly to an improved arrangement for threading in when stretching as, for example, in draw twisting.

In the draw twisting of yarns such as nylon a running yam is stretched between two rollers operated at a difference in peripheral speed and the stretched yarn is then led to the twisting spindle. In the case of high denier high strength yarns, the threading of the draw godet is very dangerous since the tension and strength of theyarns is ample to bring about amputation of the operator's fingers. For this reason it has been customary to use machines for threading the draw godet, one example of such a machine being shown in the patent to Lichtenberg, Patent No. 2,491,569.

In the Lichtenberg patent the yarn is first wound around a ring which surrounds the draw godet. The ring is then axially displaced and the yarn loops fall onto the godet for propulsion thereby. While this arrangement provides adequate operator safety, the shifting of the ring introduces an added step to the process.

It is an object of the present invention to simplify the threading of draw devices whereby the threading in can be quickly and conveniently accomplished without hazard to the operator.

Other objects and advantages of this invention will be apparent upon consideration of a preferred embodiment thereof in conjunction with the annexed drawings where- Figure l is a schematic perspective view of apparatus employed in the draw twisting of nylon, the improvement of the present invention being shown in the position assumed thereby after the threading is complete;

Figure 2 is a perspective view on an enlarged scale of the improvement of the present invention showing it in the position which it assumes during threading in; and

Figures 3, 4, 5 and 6 illustrate successive steps of threading in a godet according tothe teachings and the principles of the present invention.

Referring now in detail to Figure 1, the numeral 10 designates a high strength nylon yarn which is being stretched prior to twisting. The yarn is led through a pigtail guide 11 to a feeding roller 12, around a draw pin 13, around a godet 14 and through a pigtail guide 15 to the twister, not shown. The feeding roller 12 delivers the yarn to the draw pin 13 and, to prevent slippage, a pressure roller 16 rides in peripheral contact with the delivery or feeding roller 12. A helically shaped yarn guide 17 is located between the pigtail guide 11 and the pressure roller 16 in order that the yarn may be wrapped several turns around the pressure roller l6without having the consecutive coils in contact with one another. 'Spacing of the yarn on the draw godet is accomplished in the conventional manner by the use'of spaced cylinders 18 and 19 having axes slightly askew in order to cause the successive coils of yarn wound therearound to follow a helical path. The cylinder 18 is positively driven and the cylinder 19 is freely rotatable.

2,855,749 Patented Oct. 14, 1958 2 In Figure 1, it will be recognized that the yarn is shown in the running condition after the draw device has been threaded up. It will also be recognized that the peripheral speed of the cylinder 18 is in excess of that of the roller 12 so that stretch occurs between these two rollers around the draw pin 13, as is conventional in this art. In view of the strength of nylon, which is con siderable, and the heavy tension imposed thereon, it will be appreciated that the pressure of the coils of the yarn 10 around the godet 14 is quite high. Accordingly, the threading up of this godet is a dangerous operation, the safety of which is considerably enhanced by the present invention. According to the present invention, there is provided adjacent to the godet 14 an auxiliary yarn guide arm 20 in the form of a little hoolr which is mounted to swing from the yarn releasing position shown in Figure l to the yarn engaging position shown in Figure 2.

The guide arm or hook 20 is pivotally mounted on a cylinder 21 which is mounted for rotation in a tube or sleeve 22. Within the sleeve or tube 22 there is located a coil spring 23 which acts to bias the cylinder 21 downwardly as it appears in Figure 2. The sleeve 22 is, of course, provided with a cap which is omitted in the patent drawings for convenience of illustration. It is to be understood that the spring 23 runs between the cap, not shown, and the top of the cylinder 21 in compression so that it exerts a downward force on the cylinder 21 but does not impose a torque thereon tending to rotate it about'its axis. A slot at 24 is cut in the sleeve 22 and this slot extendsfor about and is provided with an axially extending notch at 25 which will receive the arm 20 and hold the same against rotation. The slot at 24 extends in such a way that when the arm 20 is in the position that has been drawn in full lines, it extends approximately parallel to the axis of the stretching cylinder 18 whereas, upon being brought into the other end of the slot it crosses said axisat approximately right angles and points to the stretching cylinder 18. This latter position is shown in broken lines. When the arm is in the full line position of Figure 2, it is biased into the notch by the thrust of the spring acting on the cylinder 21 from which the arm 20 projects. Thus rotation of the arm 20 from the full to the broken line positions is resisted to a degree determined by the contours of notch 25 and the thrust of the spring 23. This resistance is so chosen that it can be overcome by the tensioning effect of the godet 14 when it is drawing yarn from the pin 13.

With the assembly of the guide arm 20' in full line position, a typical threading in operation can be described. Reference is first made to Figures 1 and 3. The yarn 10 is in an untensioned condition wrapped around the rollers 12 and 16 and the yarn guide 17 as well as the draw pin 13 in the manner shown in Figure 1. The yarn is then led straight from the draw pin 13 through the pigtail guide 15. Since the roller 12 is delivering the yarn at a speed compatible with the spinning speed, the yarn is not tensioned and these operations can be performed without danger to the operator. With the yarn running in the Figure 3 position, the operator pulls a loop between the draw pin 13 and the guide 15 and passes this loop under the arm 20 and around the idler cylinder 19 of the godet 14, see Figure 4. The arm 20 is, under these circumstances, latched in the full line posi' tion of Figure 2. The operator lets go of the yarn after he has passed it over the top of the driven cylinder 18 and when he does let go the yarn assumes the path shown in Figure 5. The operation of the cylinder 18 causes tensioning of the yarn enough to overcome the action of spring 23 so that the arm 20 is moved to the broken line position of Figure 2 and causes the looito be complete on the cylinder 18, see Figure 6. The e of the swing- 3 able auxiliary yarn guiding arm 20 positively prevents the yarn from wrapping itself around the stretching cylinder 18 of the godet 14 during threading in. This difficulty could otherwise arise due to the fact that at the moment when the stretching starts the yarn speed suddenly increases considerably whereas the collecting speed of a twisting bobbin arranged after the stretching device adapts itself only slowly to the new yarn speed. As soon as the collecting speed has adapted itself, the stringing of the following yarn windings on the stretching roller without the use of auxiliary yarn guide does not present any further diificulties.

In the embodiment according to the figures only one swingable yarn guide is provided, but in other embodiments of the stretching device it may be useful to have more of these swingable auxiliary yarn guides. Further I it is possible to swing away the auxiliary yarn guide(s) by exercising by hand an increased pull on the yarn which has been strung on the yarn guides and which is not yet in contact with the stretching cylinder, which procedure should be considered for example in case a yarn is entirely kept out of contact with the stretching cylinder by the auxiliary yarn guides. In the latter case the yarn could be strung at once with more than one loop around the stretching cylinder.

What is claimed is:

I. In apparatus for tensioning yarn that includes means presenting a'yarn drawing surface rotatable about an axis, the improvement that comprises a yarn guiding arm adjacent to said means, means at one end of said arm mounting the same for movement from a first position generally parallel to said axis to a second position generally normal to said axis with the free end of said arm closer to said surface, and means releasably, resiliently latching said arm in said first position with a force less than the component acting on the arm when yarn is drawn to said surface over said arm.

2. In apparatus for tensioning yarn that includes a yarn drawing godet comprising a driven cylinder and an idler cylinder the improvement that comprises a yarn guiding arm, means mounting said arm from one of its ends for arcuate movement from a first yarn engaging position substantially parallel to the axis of said godet to a second yarn releasing position with the free end of said arm nearer to and pointing toward said godet, and means for releasably holding said arm in said first position against a predetermined thrust tending to move said arm to said second position.

3. In apparatus for tensioning yarn that includes a yarn drawing godet comprising a driven cylinder and an idler cylinder, the improvement that comprises a yarn guiding arm, means mounting said arm from one of its ends for arcuate movement from a first position substantially parallel to the axis of said godet to a second position with the free end of said arm nearer to and pointing toward said godet, the yarn guiding surface of said arm in said first position and the 'yarn receiving surface of said idler cylinder lying in alignment on opposite sides of said driven cylinder to define a yarn path extending from one side of said driven cylinder to the other but out of contact with the same, and means for releasably holding said arm in said first position against a predetermined thrust tending to move it to said second position.

4. In apparatus for tensioning yarn that includes a yarn drawing godet comprising a driven cylinder and an idler cylinder arranged substantially parallel to one another, means defining a yarn path adjacent to said driven cylinder on the side thereof opposite to said idler cylinder, a swingable yarn guide adjacent to said yarn path and on the same side of said driven cylinder, a straight line between said yarn guide and said idler cylinder bypassing said driven cylinder, and means releasably, resiliently latching said arm against swinging movement to release said yarn.

5. A self-releasing yarn guide for use in threading in draw twisters comprising an arm, means pivotally mounting said arm at one end only thereof for angular movement between a yarn engaging position ancl a yarn releasing position about an axis generally normal to the plane of movement of the arm, and means releasably, resiliently holding said arm in said yarn engaging position.

6. A self-releasing yarn guide for use in threading in draw twisters comprising a cylinder, a sleeve mounting the cylinder for rotation, said sleeve having a slot therein extending for about 90, an arm having one end anchored in said cylinder and projecting through said slot, said slot having a notch therein at one end, a spring bearing on said cylinder in a direction to bias said arm into said notch.

7. The method of threading a draw off godet including driven and idle cylinders located between a draw pin and a guide that comprises pulling a loop in the yarn running between said pin and guide in a direction away from said driven cylinder, temporarily holding said loop while drawing a second loop between said held point and said idle cylinder on the other side of said driven cylinder, and then passing the second drawn loop over said driven cylinder while releasing said temporary hold upon achievement of a predetermined yarn tension.

References Cited in the file of this patent UNITED STATES PATENTS 2,491,569 Lichtenberg Dec. 20, 1949 2,585,962 Perry Feb. 19, 1952 2,757,433 Lenk Aug. 7, 1956 f FOREIGN PATENTS 34,594 France ..,Feb. 26, 1929 

